(a) Field of the Invention
The present invention relates to a welding gun alignment detection device capable of inspecting whether a pair of upper and lower tips that are aligned straight in a spot welding gun is matched.
(b) Description of the Related Art
A type of resistance welding technology called spot welding involves a technique for welding metal sheets by first pressing a pair of upper and lower tips when the metal sheets are inserted between the tips while being folded by two or three sheets and then applying a current to the pressed tips to generate resistance heating at a contact surface. During the spot welding, a distribution of current flowing in a metal member and a pressing force has a significant impact on the quality of welding. Additionally, a shape and an alignment of the upper and lower tips contacting the metal sheet are also factors that affect the quality of welding. A robot system configured to include an industrial articulated welding robot having a repeated position error of about 0.05 mm, a spot welding gun, a tip dresser, and other peripheral devices are used to produce welding products.
After beginning a welding operation, a welding robot with the spot welding gun transfers a welded part of a tip to the tip dresser. The tip dresser removes any deformation and an oxide film from the welded part of the tip that may be caused by pressing and heating. The tip dresser also processes the welded part of the tip to recover the tip's original shape. A central axis line of the tip matches an aligning reference line X-X of the tip that is set in the welding robot to adjust a moving position of the tip. However, a length of the tip may decrease over time due to continued use, at which point the tip may need to be exchanged with a new tip. In the exchange process, a holder part of the spot welding gun may bend and the upper and lower tips may become mismatched due to pressure and high heat during the welding. A welding operation may not be possible when the upper and lower tips of the spot welding gun do not match the aligning reference line X-X, and the shape of the welded part may not be able to be cut when the tip dresser dresses the upper and lower tips simultaneously, leading to welding defects.
The upper and lower tips of the spot welding gun are set widely apart from one another. A worker therefore may not be able to confirm visually whether the central axis line of the tips is mismatched compared to the aligning reference line X-X. As a result, the misalignment may cause welding defects that may only be found when the worker examines the welded state of a product after the welding operation has been completed. Only discovering welding defects after products have been welded may cause problems, a waste of time, and an economic loss.
The above information disclosed in this section is merelyto assist in understanding the background of the invention and should not be interpreted as limiting the disclosed subject matter provided herein in any way.